Scientists examine numerous specimens placed on slides using microscopes. Typically, a specimen is covered with a thin transparent coverglass. This is done for several reasons. The coverglass can flatten the specimen so that the specimen is in the same viewing plane, thereby allowing one to view the specimen better. The coverglass provides protection for the specimen from the objective lens of the microscope should the lens be placed too closely to the slide. The coverglass may further provide a housing structure or an area by which the specimen will be permanently retained on the slide. The coverglass, in combination with a liquid adhesive, also helps to preserve the specimen for archiving purposes.
The coverglass is typically a thin, rectangular, square or round piece of glass or plastic which is placed in direct contact with and over the specimen on the slide. The coverglass comes in a variety of sizes and shapes. One example of the coverglass has dimensions of about 1″×2″ and 0.005″ to 0.009″ thick. They are packaged stacked in a vertical pile. This stacking presents a problem: the coverglasses are difficult to handle and separately remove from the stack since they are fragile and may stick together easily. Typically, to remove one coverglass from the stack, a considerable amount of bending moment is applied at the middle of the coverglass. For example, some prior art systems, such as shown in U.S. Pat. No. 5,989,386 (Elliott) use two suction cup devices on a coverglass, placed on both sides of the middle of the coverglass. The suction cups thereafter bend the coverglass, creating great stress in the middle of the coverglass in order to separate the coverglass from the stack of coverglasses. However, this action results in numerous coverglasses breaking because they are very fragile and the force applied was greater than the stability of the glass. The bending force causes a disproportionate amount of stress at the center of the coverglass. Furthermore, the bending action did not guarantee that only one coverglass was selected.
After selecting a single coverglass, the coverglass is then placed over the specimen on a slide in the presence of a liquid adhesive. This presents other problems. For example, it is important that there are no air bubbles trapped under the coverglass when it is placed onto the slide. Also, it is important not to harm the specimen in any way when positioning the coverglass onto the slide. One way to apply the coverglass was to place the coverglass on the slide, and then apply pressure onto the coverglass compress to remove trapped air bubbles. In addition, handling and separating the coverglasses at times can charge them with static electricity. Electrostatic forces can hold the coverglass to the suction cups even after turning the mechanism off, making it difficult to apply the coverglass to the slide. Moreover, the compression of the coverglass to remove air bubbles may cause the adhesive on the tissue sample to expel outward, thereby potentially contaminating other slides or other portions of the machine.
Thus, there exists a need to provide a better automated coverslipper that avoids the problems of prior art automated coverslippers.